This supplement represents a request for support to assure continuation of current lipoprotein studies underway in our long-term study of atherogenesis in the susceptible squirrel monkey and resistant cebus. It will also provide support for scanning electron microscopy of aortas from these animals. In addition it is proposed to investigate a nephritis that has been induced in squirrel monkeys and which may complicate atherosclerosis in this species. The nephritis develops when squirrel monkeys are fed a low soyprotein diet and terminates in severe oxalosis with uremia and/or nephrosis by 20-24 weeks. It is proposed to characterize this syndrome biochemically and ultrastructurally while investigating the dietary variables associated with its genesis.